console.log('123' == 123)
console.log('' == null)
console.log('' == 0)
console.log([] == 0)
console.log([] == '')
console.log([] == ![])
console.log(null == undefined)
console.log(Number(null))
console.log(Number(''))
console.log(parseInt(''))
console.log({} + 10)

let obj = {
   /* [Symbol.toPrimitive]() {
        return 200;
    },*/
   /* valueOf() {
        return 300;
    },*/
    toString() {
        return 'Hello';
    }
}

console.log(obj + 200); // 这里打印出来是多少？
